As the amount of data to be generated and processed steadily increases over time, existing database paradigms cannot meet the performance requirements to support working with big data sets. Database management systems must be able to scale to highly parallel multi-server environments where data may be read and written concurrently by multiple database instances.
An area of particular importance is the allocation and management of free space within a tablespace. One approach is to use locally-managed tablespaces, where each tablespace manages its own local free space bitmaps. In this approach, concurrent free space operations from single or multiple database instances must obtain a latch on a local free space bitmap associated with a data file, necessitating the serialization of such free space operations.
With continual exponential improvements in processor speed and memory capacities, the actual database transactions complete so quickly that the associated tablespace free space maintenance overhead becomes a noticeably larger proportion of the total processing wait time. Since free space operations must be serialized for each free space bitmap, the use of locally-managed tablespaces becomes less appropriate for tablespaces with big data sets demanding high levels of data concurrency. While attempts have been made to improve free space maintenance concurrency by manually splitting a locally-managed tablespace into several data files with independent local free space bitmaps, this fragmenting severely complicates end user database administration, management, and development tasks.
Based on the foregoing, there is a need for a tablespace free space management method that can scale to big data sets while minimizing complexity for end users.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.